The field of regenerative medicine aims to provide tissue substitutes for reconstruction secondary to trauma, disease or congenital abnormalities. While biomaterials and cells are often employed to regenerate new tissues, these methods tend to be costly and require significant time for new tissue formation. Restoration of soft tissue form is critical for a number of applications including trauma reconstruction, breast reconstruction, and cosmetics (nasolabial folds, wrinkles, etc). In general there are two approaches today; 1.) injection/transfer of biological tissue (fat) or 2.) injection or implantation of a synthetic or naturally derived material. In both cases, the transplanted tissue or biomaterial will eventually be degraded and replacement is required.
Reconstruction using patient tissue can provide permanent restoration of tissue in some situations. However, such procedures also have their limitations. Breast reconstruction after mastectomy can include the use of tissue flaps of muscle and adipose tissue either from the abdomen or back which are pulled over to the reconstruction site. Such flaps are necessarily limited in size by the amount of tissue present in the woman for use, and transfer of muscle from the abdomen or back can extend recovery time and result in donor site morbidity. The persistence of fat transfer varies widely with reports of anywhere between 30-90%. Persistence is also often surgeon and technique dependent. Such loss of persistence requires multiple procedures to maintain the desired correction. The donor site morbidity associated with autologous fat transfer is also a significant concern. In addition, implanted adipose tissue often leads to post-operative calcifications. This phenomena is of particular importance for women with a history of breast cancer undergoing breast reconstruction following mastectomy, as the calcifications may interfere with mammography readings and result in multiple, unnecessary breast biopsies and anxiety. Finally, for many patients undergoing chemotherapy and radiation for cancer, the associated cachexia leaves them without the adipose volume they would require for autologous fat transfer.